ORIGINAL: rgburrill
I don't get it. Changing carbs, adding flywheels, changing heads? How does this provide any comparison between engines? Why not just get an older car/truck/buggy, put your test engines in it and run the heck out of them?
I personally would want to simply break the engine in, only because I don't think a car engine gets to its peak during break in and it should, IMO.
I can see the reasoning behind what the OP wants to accomplish. It's no different than testing a certain prop on more than one engine to suit a specific aircraft.